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The universe is said to be created 14 billion years ago by the Big Bang Theory. The universe was so powerfully hot and dense, that atoms could not endure it. Scientists believe that the whole visible universe was as meager as a grain of sand. When the universe decided to stretch out, it became much cooler and then atoms and molecules began to take shape. Gravity attracted matter into clumps developing the planets and stars we all know today.
An Attraction
All articles of objects push and pull on one another by a force called gravity. Gravity is responsible for keeping the universe in check. It keeps the planets from spiraling off into space. The more matter or mass something has, the more gravitational pull it has. That matter could be anything from visible matter to invisible matter called dark energy. The closer objects are to each other the more they have an attraction to each other. All this pulling in the universe creates a drag that “should” be slowing down the universe. Why So Slow?
In the late 20th century, astronomers found that the universe has so much mass to slow the expansion of our universe but not enough to stop it all at once. By the 1990s, astronomers knew the degree of the expansion and wanted to know how much it has leisurely lingered over billions of years. Astronomers observed an erupting star called type la supernovae that could help scientists determine colossal distances over space as well as the expansion of the universe. Finding these exploding stars was hard work at first because the star only lasts a couple of weeks before its glow is gone. When scientists found it easier to find these stars with advanced telescopes, they found that the stars were a lot dimmer than expected. They had to be further away because of how dim they were. If this were true that means the universe had to be speeding up, not slowing down. Scientists were puzzled. Gravity doesn’t push things apart, it pulls them together.
Unknown Force Scientists thought the fate of the universe would be The Big Chill. In accordance to this theory, the universe should be more slowly expanding today then it did in the past because of gravity acting on everything and slowing everything down. The problem is that astronomers found the universe was doing the opposite. Instead it was moving faster today then it did in the past, There had to be a strange unknown outside force causing this. Scientists all over the world discussed this new discovery and were astonished, trying to take grasp over this. Some astronomers were very doubtful of the universe’s accelerating expansion. Teams that had been observing these distant supernovae thought that maybe they were from an earlier time in the universe. They even thought maybe they were comic dust from galaxies or in between galaxies, making the explosions appear to us, to be faint.
Discovery
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The High-z Team in 1998 and the Supernovae Cosmology Project in 1999 was the first research to reveal that the universe is not only expanding but it’s accelerating. The High-z Team first thought that the universe was decelerating as well, due to its own mass. How we know the universe is expanding is because of the vagueness of a distant la supernova. The brightness tells us its caliber. A type la supernova is the result of a carbon-oxygen white dwarf star growing in mass until it goes to Chandrasekhar limit. This is when the mass is so big that the electron degeneracy pressure within the core of the star is too insufficient to stabilize the star’s gravitational attraction to itself. Then the dwarf is engulfed by a runaway thermonuclear explosion which then reaches a climax of luminosity of more than 4 billion time’s the Sun’s luminosity. They are so bright that are seen by the Hubble Space Telescope of about 75% across the universe. They are the tools that help show great distances within space.
It's Dark Energy!
Scientists turned to the Hubble Space Telescope, the only telescope advanced enough of to see supernovae in detail. In 2000, a team under Saul Perlmutter, observed about a dozen supernovae and detected no comic dust that ruled out the reason for the explosions dimness. In 2002, another team was put together by Adam Reiss. They observed 25 supernovae and found their light had been traveling for billions of years. The observations showed that the accelerating universe was because of the power of dark energy.
What is in our Universe?
Courtesty of http://www.scienceprogress.org/2008/01/flying-the-right-mission/
The first person to think of empty space as something and not nothing was Albert Einstein. The subject of dark energy and dark matter rose and has driven scientists because it's such an intriguing and unknown subject. Many believe the theory is true and others believe it is nothing but a theory. More is unknown that known about this "dark" subject. What we know is how much there is of dark energy because it affects the universe's expansion. Dark energy is a hypothetical form of energy that is the cause for this accelerating universe. This is the most accepted theory for the reason of expansion. The two forms of dark energy are the cosmological constant and scalar fields. The “cosmological constant” was first proposed by Einstein. It was an adjustment from his other theory, “general relativity” to explain a “stationary universe”. The cosmological constant is a constant energy density that fills space and it is almost similar to vacuum energy. Vacuum energy exists in space as an underlying background energy. Scalar field’s energy density can distort in space and time. Dark energy also is sometimes called a quintessence. A quintessence is another hypothetical manifestation of dark energy to describe observations of the stretched out universe. The nature of dark energy is questioned. It is not very dense and is homogeneous and because of this, it is very hard for scientists and astronomers to imagine to perform laboratory experiments to identify it. Dark energy also has powerful negative pressure. Astronomers think that because of the negative pressure in dark energy, it is the cause of the expanding universe and the reason for gravity to hold galaxies together. Dark matter and dark energy are misused by people as being the same thing. Einstein’s theory relates matter and energy as separate materials of the same thing, but scientists aren't sure if they are expressions of the same "thing". They know they exist, but know little about their internal fabric. Researchers have tried to put dark energy and dark matter together as the same thing but they simply are not. One theory is a scalar field because this field has energy, magnitude and pressure, but because it has no direction it is a scalar. String theories try to relate to dark matter with super symmetric particles but it makes no relation to dark energy. For now, we think of them as
individuals. “Scientists believe that 0.03% of the universe is composed of heavy elements, 0.3% neutrinos, 0.5% stars, 4% free hydrogen and helium, 25% dark matter, and 70% dark energy” (curious.astro). 5% of the universe is normal matter, which maybe isn't so normal since there isn't that much of it. Normal matter is the planets, so now you can only imagine how big the universe really is. Dark matter was introduced by Fritz Zwicky in 1934 for an explanation on “missing mass”. Dark matter is matter, unlike dark energy which is energy. Dark matter is the cause of galaxy formation and structure formation. Dark matter also is the cause for exaggerated fluctuations in the cosmic microwave background. It derives from gravitational causation in background radiation and visible matter. It can not be detected due to scattered electromagnetic radiation. This is a type of energy that has behavior that is wave-like as it voyages through space. There are two forms of dark energy called baryonic and nonbaryonic. Baryonic dark matter is made up of normal matter but also produces almost no electromagnetic radiation. Nonbaryonic dark matter is not formed of atoms and is believed to be composed of most of the universe. It's amazing to think that only 20% of the universe is normal matter and nearly 80% is dark matter.
The Fate of the Universe
Courtesty of http://www.scienceprogress.org/2008/01/flying-the-right-mission/
Everyone wonders what could be the fate of our universe, the thing that is bigger than what we realize. Evidence has ruled out The Big Crunch, where the universe re-collapses. Since the universe is expanding at a fast rate our fate has even gone past The Big Chill, where the universe expands more slowly. Now they believe the fate is The Big Rip. This theory states that with dark energy, as the universe expands faster and faster, gravity’s work will be all undone. Clusters of galaxies will separate from each other and galaxies will be torn apart. Everything from planets and stars to atoms and molecules will be ripped and shredded apart. Our universe was born in a violent expansion that could die in an even more violent expansion. Out of the three scenarios and which ever will happen, it all depends on what dark energy really is. The universe has tens of billions of years left and that gives us plenty of time to look for the right answer.
- - -. “Dark Energy, Dark Matter.” science.nasa.gov. N.p., n.d. Web. 16 Mar. 2011. <http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/>. Overbye, Dennis. “Dark, Perhaps Forever.” nytimes. N.p., 3 June 2008. Web. 16 Mar. 2011. <http://www.nytimes.com/2008/06/03/science/03dark.html?pagewanted=1>. Riess, Dr. Adam, and Nancy Riess. “Dark Energy.” stsci.edu. Adam Riess, n.d. Web. 16 Mar. 2011. <http://www.stsci.edu/~ariess/darkEnergy.htm>. Stierwalt, Sabrina. “Curious About Astronomy? Ask An Astronomer.” Curious.astro.cornell.edu. N.p., July 2004. Web. 16 Mar. 2011. <http://curious.astro.cornell.edu/question.php?number=634>. Travers, Bridget, and Jeffrey Muhr, eds. Scientific Milestones and the People Who Made Them Possible. Detroit, MI: Gale Research Inc., 1994. Print. World of Scientifc Discovery.
Table of Contents
The Big Bang!
An Attraction
All articles of objects push and pull on one another by a force called gravity. Gravity is responsible for keeping the universe in check. It keeps the planets from spiraling off into space. The more matter or mass something has, the more gravitational pull it has. That matter could be anything from visible matter to invisible matter called dark energy. The closer objects are to each other the more they have an attraction to each other. All this pulling in the universe creates a drag that “should” be slowing down the universe.
Why So Slow?
Unknown Force
Scientists thought the fate of the universe would be The Big Chill. In accordance to this theory, the universe should be more slowly expanding today then it did in the past because of gravity acting on everything and slowing everything down. The problem is that astronomers found the universe was doing the opposite. Instead it was moving faster today then it did in the past, There had to be a strange unknown outside force causing this. Scientists all over the world discussed this new discovery and were astonished, trying to take grasp over this. Some astronomers were very doubtful of the universe’s accelerating expansion. Teams that had been observing these distant supernovae thought that maybe they were from an earlier time in the universe. They even thought maybe they were comic dust from galaxies or in between galaxies, making the explosions appear to us, to be faint.
Discovery
It's Dark Energy!
Scientists turned to the Hubble Space Telescope, the only telescope advanced enough of to see supernovae in detail. In 2000, a team under Saul Perlmutter, observed about a dozen supernovae and detected no comic dust that ruled out the reason for the explosions dimness. In 2002, another team was put together by Adam Reiss. They observed 25 supernovae and found their light had been traveling for billions of years. The observations showed that the accelerating universe was because of the power of dark energy.
What is in our Universe?
The Fate of the Universe
Everyone wonders what could be the fate of our universe, the thing that is bigger than what we realize. Evidence has ruled out The Big Crunch, where the universe re-collapses. Since the universe is expanding at a fast rate our fate has even gone past The Big Chill, where the universe expands more slowly. Now they believe the fate is The Big Rip. This theory states that with dark energy, as the universe expands faster and faster, gravity’s work will be all undone. Clusters of galaxies will separate from each other and galaxies will be torn apart. Everything from planets and stars to atoms and molecules will be ripped and shredded apart. Our universe was born in a violent expansion that could die in an even more violent expansion. Out of the three scenarios and which ever will happen, it all depends on what dark energy really is. The universe has tens of billions of years left and that gives us plenty of time to look for the right answer.
Works Cited
NASA. “Dark Energy.” hubblesite. N.p., n.d. Web. 16 Mar. 2011. <http://hubblesite.org/>.
- - -. “Dark Energy, Dark Matter.” science.nasa.gov. N.p., n.d. Web. 16 Mar. 2011. <http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/>.
Overbye, Dennis. “Dark, Perhaps Forever.” nytimes. N.p., 3 June 2008. Web. 16 Mar. 2011. <http://www.nytimes.com/2008/06/03/science/03dark.html?pagewanted=1>.
Riess, Dr. Adam, and Nancy Riess. “Dark Energy.” stsci.edu. Adam Riess, n.d. Web. 16 Mar. 2011. <http://www.stsci.edu/~ariess/darkEnergy.htm>.
Stierwalt, Sabrina. “Curious About Astronomy? Ask An Astronomer.” Curious.astro.cornell.edu. N.p., July 2004. Web. 16 Mar. 2011. <http://curious.astro.cornell.edu/question.php?number=634>.
Travers, Bridget, and Jeffrey Muhr, eds. Scientific Milestones and the People Who Made Them Possible. Detroit, MI: Gale Research Inc., 1994. Print. World of Scientifc Discovery.